/*!
@defgroup api API
 
 api
 
 API is the system call of the rDSN micro-kernel, which is used to develop applications, frameworks, tools, and local runtime libraries. 
 
@{
@defgroup service-api Service API

service api.

 Service API is used to build applications and distributed frameworks atop rDSN.                                                
 
 
 @defgroup tool-api Tool API

 tool api.

 Tool API is used to build local libraries (e.g., network libaries, locks), development/operation tools, and runtime policies.
@}
 
 */
